As the title says: PAC 1519 or Manley 221438?

The specs are pretty much the same (at least for my application), use will be with a .590 lift cam and 7100 RPM redline (stock LS7) street car only (may seem some very limited road course use).

Of course the PAC is nitrided, and I don't know what the Manley "super finish" is (only that it costs more). Could be nitriding? Would prefer the longest lasting spring of the two.

 

pacs or even consider the psi ml1511s....

 

Have you also considered BTR platinum springs? They have had a "0" failure rate. Just my .2 bud I know they weren't in your list.

 

I'm running 1519's with .650 lift. Springs were pulled at 3,000 miles and lost no pressure or rate. It seems the key to making a beehive work is a light valve train

 

Thanks for the input, guys. The PSI 1511's aren't going to give me the balance in pressures I'm looking for (seat/open) and all I should need for a 74 gram valve is a beehive (altho Brian has an excellent price on his spring packages).

I am indeed trying to keep the valvetrain light as possible; I'm planning to use a heavier than stock rocker but am saving weight elsewhere to offset it. Regardless, I'm shooting for seat and open pressures about 20 lbs over stock just for a bit of margin (115/316 on the stock spring at the default install height w/.600 lift).

Looks like the nod is going to go to the PAC's. I couldn't find a weight on the Manley springs so I called them up. The guy on the phone didn't know either, but he promptly got one out of stock and weighed it -- 73 grams. How's that for customer service . . . . unfortunately he didn't know what the Manley 'super finish' was, so that remains a mystery. Considering that, and the weight, the 67 gram PAC's seem to be the more desirable of the two for my particular situation.

 

Be careful with a heavier rocker. Weight over the nose isn't good for control

 

Like Outcast said, what rockers are you running? If your going with a roller design, you will need duals.

 

Mentioned in another thread, the YT 6670 Yella Terra's for the LS7. See https://ls1tech.com/forums/generatio...la-terras.html

Best I can determine (without handling in person) the nose weight of those are about 12 grams over stock. I can save 5 grams by going to a titanium retainer, and it seems that I can save about 8 grams by going to a lighter spring (some debate on the issue of spring weight importance/impact). So, in my book 12 - 5 - 8 = wash.

That, plus a bit more pressure on the seat and open (over stock) should keep things happy. I think . . . . .

Edit: Unless, the length of the axis of rotation of the rocker nose (1+") gives it a much larger moment of inertia compared to the spring and retainer just moving 0.60" up and down. Hmmmm